Many solutions exist in the literature using Magnetic Resonance techniques to analyze directly on the liquid pipe and in real time, different properties of the transport and/or production of fluids. We can for instance mention:
1. Up from the measurement of the relaxation times T1 and T2 and from the coefficient of Molecular diffusion D, the petrophysical properties of the extraction fluid are measured in real time and in the real conditions of reservoir, including:                a. the level of contamination of the fluid due to, by example, filtrations of water, mud, etc.;        b. viscosity and the relation water/gas/petroleum.        
These measurements are made in surface as well as in the pit (continental or offshore) and eliminate ambiguities associated with samples extraction as well as the corresponding transport procedures. Some analytical methods based on the Magnetic Resonance and its associated devices are described, for example, in the U.S. Pat. No. 6,111,408, “Nuclear Magnetic Resonance Sensing Apparatus and for Techniques down hole Measurements”, by T. Blades et al.; U.S. Pat. No. 6,737,864 B2, “Magnetic Resonance Fluid Analysis and Method”, by M. G. Prammer et al.; U.S. Pat. No. 6,825,657 B2, “Magnetic Resonance for Method Characterizing Fluid Samples Withdrawn from Subsubsurface Earth Formations”, by R. L. Kleinberg et al.; U.S. Pat. No. 6,891,369 B2, “Magnetic Resonance Method and Logging for Apparatus Fluid Analysis”, by M. D. Hurlimann; U.S. 2005/0040822 A1 “Multi-measurements NMR Analysis based on Maximum Entropy”, by N. Heaton and 2006/0122779 U.S.A1 “Interpretation for Methods NMR Diffussion-T2 Maps” by Chang Cao Ming and N. Heaton and the therein contained references
2. Another group of tools, also based on the Magnetic Resonance technique, has been divulgated, to determine the cut (or proportion of petroleum and water) and the flow in the fluid vein. On the one hand, the determination of petroleum and water cut is generally is carried on by the Magnetic Resonance signal weighted by the individual spin-lattice relaxation times T1 of the fluid. In particular, for the case of a mixture of petroleum and water, water T1 differs from those of petroleum. Moreover, it is also possible to measure the cut of the light and heavy elements of petroleum, since its T1 values differ enough to isolate the different MR signals. See by example the U.S. Pat. No. 4,785,245. On the other hand, for the flow-rate measurement, three different basic principles can be grouped:
The measurement of the fluid flow-rate through the measurement of the “flight time” of the fluid between two Magnetic Resonance spectrometers: (or between two sensors of a same spectrometer). See the U.S. Pat. No. 6,046,587 “Measurements of Flow Fractions, Flow Velocities and Flow Rates of a Multiphase Fluid using NMR Sensing” and the U.S. Pat. No. 6,268,727 “Measurements of Flow Fractions, Flow Velocities and Flow Rates of a Multiphase Fluid using ESR Sensing”, by J. D. King, Q. Nor and A. De los Santos, which disclose a sensor that uses at least two MR spectrometers or one MR and another Electron Paramagnetic Resonance one. The basic principle of the measurement methodology is based on what is known as the “flight or passage time” of MR-excited fluid nuclei between both MR spectrometers. Another variant is the US Patent Application No. 2004/001532, by M. Ramia, D. J. Pusiol, C. A. Martin, E. Fried and R. Garnero, “Method and procedure to measure fluid flow and fluid fraction, and equipment used to that end”. In this case there is only one electronic part, shared by two sensorial coils, being the operation principle the same as the one described before; namely, the speed of the flow through flight time of the water and petroleum molecules in the space between both sensorial coils is separately measured. Those are little practical and expensive to be implemented, as well as of difficult application in petroleum fields with rigorous climatic conditions generally.
Another methodology is based on the spatial encoding of the flow velocity by a magnetic field gradient in the direction of the flow. The gradients (static and/or electronically pulsed) are employed to modulate the protons spin precession phase. It means that the spatial codification is made in what it is known as the Laboratory Frame. The flow meter with fluid phase separation that uses the pulsed electromagnetic field gradient is disclosed, for instance, by the U.S. Pat. No. 6,452,390, by E. Wollin, “Magnetic Resonance Analyzing Flow Meter and Flow Measuring Method”. This method has the disadvantage that, at the speeds at which the protons commonly move in the magnetic field when the fluid flow-rate is measured under reservoir conditions, is too fast. Therefore, the application of fast rise time magnetic field gradients switching on and off is of difficult technological implementation. This means that this methodology is generally restricted to measurements at relatively low flow-rates. Another variant which avoids high electric currents by including a permanent longitudinal gradient field is described in the US Patent Application No. US 2006/0020403, by D. J. Pusiol “Device and Method for real time direct measurement of the Flow-Rate of a Multi-Component Complex Fluid”. This invent divulgates a flow meter and a cut sensor constituted by only one coil associated to a magnet of slightly oblique flat polar faces. The device generates a constant magnetic field, in addition with a magnetic field gradient in the direction of the flow. The spatial codification of the temporal position of the resonant nuclei is done by a linear magnetic field gradient in the volume that occupies the excitation/detection Magnetic Resonance coil. For high flow speeds, this gradient must be increased to reach the necessary effectiveness in the space codification process of the protons that compose the circulating complex fluid. But the increment of the magnetic field gradient strength implies a broadening in the MR line width. Therefore, the MR signal to noise ratio deteriorates. The maximum limit of the flow that is possible to be measured by the mentioned invention is determined by the maximum value of the magnetic field gradient that is possible to apply to the fluid, before the signal is deteriorated so that the required precision is not anymore reached for this particular use.
All the above described solutions measure only the average of flow-rates of the fluid components, but to evaluate the efficiency of the methods of extraction, pumping, transport, water injection in secondary extraction, etc., it is necessary to be able to evaluate, in the line and in reservoir conditions, the flow regime of the fluid. Therefore, it is also necessary to know the velocity profile of each individual component of the fluid in spatially selected volume elements.